Apparatus for etching printing-plates.



A. H. COOMBS. APPARATUS FOR ETCHlNG PRINTING PLATES.

APPLICATIONIFILED MAY 26. 1913- 1,147, 145. Patented July 20, 1915.

COLUMBIA PLANOCIRAPH RIO-,WASHINGTON. D. c'.

J OFFICE.

APPARATUS FOR ETGI-IING- PRINTING-PLATES.

specification of Letters Patent. Patented July 20, 1915.

Application filed Ma 26,1913. seriainojzeasis. 7

To all whom it may concern:

Be it known that I, ARTHUR H. COOMBS, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook,-and State ofIllinois, have invented certainnew and useful Improvements in Apparatusfor Etching Printing-Plates, of which the following is a specification.

-The main objects of this invention are to provide an apparatus for usein etching relief plates in printing, adapted to prevent undercutting ofthe relief portions of the plates and to permit the plates to be etchedwith rapidity and evenly. 7

An illustrative embodiment of this invention is shown in theaccompanying drawings, in which Figure 1 is a side elevation partly insection of an apparatus constructed according to this invention. Fig. 2is a transverse vertical section of the same. Fig. 3 isan end View.

. It is known that in etching plates undercutting may be avoided to agreat extent by quickly etchingthe plates in a solution of comparativelystrong acid, but this method has the disadvantage that the plates arenot always evenly etched. It is also known that the plates may be moreevenly etched by immersing them for a considerable length of time in aweak acidsolution, but in this process undercutting occurs to anundesirable extent and the process requires too much time to bepractical for many classes of work.

Thepresent invention relates to an apparatus for causing, a flow of acidin varying directions over a substantially horizontally disposed plate,whereby little if any undercutting occurs and the plate may be etchedevenly and with rapidity. To further. this end the apparatus is designedtoautomatr cally tilt from side to side, so that the etching solutionmay act evenly on various portions of the plate.

Printing plates are sometimes etched whe resting on edge in an uprightposition, while the etching liquid is permitted -to run down over thesurfaces of the plates, but by this method there is danger of unevenetching and undercutting. The undercutting with this arrangement may bedue to the tendency of the liquid to run more around the edges of raisedparts of the plates than to run evenly over its entire surface. Thelatter may more easily occur when the plate lies in a substantiallyhorizontal position.

Referring to the drawings, a suitable supporting frame 1 for theentireapparatus is shown with a pair of bearings 2 and 3, through which passesa horizontally disposed shaft'l. Between the bearing 3 and the shaft isa rotatable sleeve 5 to which is rigidly secured a ulley 6 and areel-shaped receptacle frame consisting of a pair of star-shaped endpiecesS and 9 and a plurality of tie-rods 10. The end piece 8 isrotatable upon-the shaft l while the end piece 9 is secured to sleeve 5"Supported in the frame 7 between the rods 10 is a cylindricalreceptacle 11 consisting of non-corrosive material, such asearthen-ware, or it may be made of metal lined with porcelain or someother acid resisting material. The receptacle 11 preferably has closedends 12, but is provided with a rectangular opening 13 which is normallyclosed by a glass lid 14 hinged to one of the rods 10 at one side, andclamped in its seat at the other side by means of clamps 15. The lid 14is preferably provided with an elastic gasket 16, as shown in Fig. 1.Thereceptacle 11 is provided with a plurality of bucket or cupshapedprojections 17 extending along its length and suitably formed to providepockets 18 by means of which the etching acid 19 may be lifted from thebottom of the receptacle and deposited on the article to be etched,indicated by broken lines 20 (Fig. 2), resting'on a suitablesupportingtray'21. This liftingof the acid is eflected by rotating thereceptacle'1l,as described further on. The tray 21 is rigidly secured toshaft 4:, and like the casing of the receptacle 11 is made of acidresisting material. The shaft 4 at its left hand edge (Fig. 1),preferably outside ofthe receptacle 11, carries a pendulum 22 which maybe formed by bending the shaft 4, as at 23, and securing to the end ofthe shaft a weight 24. The functionof the pendulum is to govern therocking offthe tray 21 from side to side when the tray is set in motionby the deposit of etching liquid thereon. i

The tray 21 may be provided with up wardly extending flanges 25 at itsedges to prevent the plate which is being etched from slipping relativeof the tray. The tray preferably also has perforations 26 so that theacidmay normally drain outthetray, and to provide means whereby theetched plate may readily be removed from the tray. The tray 21, as shownin Fig. 1, may be made to extend'along almost the entire length of thereceptacle 11, and to overhang at its ends 27 inwardlyextending bosses28 integral with the ends 12 of the receptacle 11. At its inner end eachboss is provided with an annular flange 29 extending radially of shaft4:, whereby any acid that may be thrown against the end walls 12 anddrip downwardly on bosses 28 will drip off of flanges 29 rather thanmake its way to shaft 4 between bosses 29 and the tubular part 30 oftray 21 through which shaft 4 passes. The overhanging extensions 27 ofthe tray also assist in preventing the acid from reaching the metallicshaft 4:, and thereby corroding the latter.

To operate the device the etching fluid may be introduced through theopening 13 in casing 11, and the plate to be etched is also passedthrough this opening and permitted to rest on tray 21. Then the lid 14:

is tightly clamped in its closed position putting the device intocondition for operation. To perform the etching operation thecylindrical receptacle 11 is rotated by power ap plied at the pulley 6,which, as before explained, is rigidly connected to the receptacle 11 bysleeve 5 which is rotatably mounted within bearing 3 on shaft 4:.Rotation of the receptacle in the direction indicated by the arrow (Fig.2) results in the cupshaped extensions or flanges 17 each raising acertain portion of the etching fluid 19 until the projections 17 arriveabove the plate 20, when the fluid flows out of pockets 18 to the plate20 thus throwing the tray out of balance and running to one sidethereof, and increasing its tendency to rock. The action of the pendulumis to normally urge the tray toward its horizontal position and therebygovern the rocking motion of tray 21 caused by the liquid which isdeposited on the tray and flows from side to side. By this means thesolution 19 is continually agitated while acting on plate 20, andtherefore no part of the solution can for any considerable length oftime act exclusively on any one part of the plate. By this means anextremely quick acting acid solution may be employed without danger ofunduly acting on some portions of the plate. Undercutting of the raisedportions of the plate is prevented, as before mentioned, by using aquick acting solution while not permitting the plate 20 to rest for anyconsiderable length of time far out Copies of this patent may heobtained for of a horizontal position while the acid is acting on theplate.

Although but one specific embodiment of this invention has been hereinshown and described, it will be understood that numerous details of theconstruction shown may be altered or omitted without departing from thespirit of the invention as defined by the following claims.

I claim 1. In an etching apparatus, the combination of a. supportingframe and a support therein, a tray for supporting articlesto be etchedsecured to said shaft, apendulum se cured to, said shaft whereby thetray is urged to the horizontal position, and means for pouring etchingliquid on the tray whereby it isoscillated and causes the liquid to runfrom side to side over the-articles to be etched.

4:. In a device of the class described, the combination of a frame, ashaft journaled therein, a tray for supporting articles to be etchedsecured to said shaft, a pendulum secured to said shaft whereby the trayis urged to the horizontal position, and a rotatably mounted receptaclesurrounding said tray,-the interior of said receptacle being providedwith a pocket whereby when'the receptacle is rotated liquid may belifted from the bottom of the receptacle and deposited on the tray.

5. In an etchingapparatus, the combination of a supporting frame, ashaft journaled therein, a receptacle frame rotatably supported on saidshaft, a receptacle contained within said receptacle frame, pockets inthe interior of said receptacle and rotatable therewith, meansforrotating said receptacle, a horizontally disposed support secured tosaid shaft within. saidreceptacle, and a pendulum carried by said shaft.

Signed at Chicago this22nd day of May,

v 1 ARTHUR H. OOOMBS. Witnesses:

Pmmr B. WoonwoR'rH,

RUDow RUMMLER.

five cents each, by addressing the Commissioner of Patents Washington,D. G.

